Added comments following code review.

theano/gof/cc.py

@@ -906,6 +906,11 @@ class CLinker(link.Linker):
             if isinstance(i, graph.Constant): #orphans
                 if id(i) not in constant_ids:
                     isig = (i.signature(), topological_pos, i_idx)
+                    # If the Theano constant provide a strong hash
+                    # (no collision for transpose, 2, 1, 0, -1, -2,
+                    # 2 element swapped...) we put this hash in the signature
+                    # instead of the value. This make the key file much smaller
+                    # for big constant. Before this, we saw key file up to 80M.
                     if hasattr(isig[0], "theano_hash"):
                         isig = (isig[0].theano_hash(), topological_pos, i_idx)
                     try:

theano/gof/compiledir.py

@@ -107,7 +107,7 @@ AddConfigVar('compiledir',
 
 
 def print_compiledir_content():
-    max_key_file_size = 1 * 1024 * 1024
+    max_key_file_size = 1 * 1024 * 1024  # 1M
 
     def flatten(a):
         if isinstance(a, (tuple, list, set)):